I've tested Chris's clojure-string-with-no-match-returns-original-2.patch against latest github Clojure as of this morning, and the tests pass. Cool that he found a straightforward performance improvement for the no match case. The code appears correct. I also verified that for the reason Chris mentions, StringBuilder will not work as a replacement for StringBuffer. At least there will never be any contention on the locks implementing the StringBuffer synchronization the way they are used here.

Andy Fingerhut
added a comment - 28/Nov/11 5:09 PM - edited I've tested Chris's clojure-string-with-no-match-returns-original-2.patch against latest github Clojure as of this morning, and the tests pass. Cool that he found a straightforward performance improvement for the no match case. The code appears correct. I also verified that for the reason Chris mentions, StringBuilder will not work as a replacement for StringBuffer. At least there will never be any contention on the locks implementing the StringBuffer synchronization the way they are used here.